package com.laz.knowledge.fortyseven;

import java.util.Random;
import java.util.concurrent.locks.ReentrantReadWriteLock;

public class ReaderWriter {
	public static void main(String[] args) {
		final Queue3 q3 = new ReaderWriter().new Queue3();
		for (int i = 0; i < 3; i++) {
			new Thread() {
				public void run() {
					while (true) {
						q3.get();
					}
				}
			}.start();
		}
		for (int i = 0; i < 3; i++) {
			new Thread() {
				public void run() {
					while (true) {
						q3.put(new Random().nextInt(10000));
					}
				}
			}.start();
		}
	}

	class Queue3 {
		private Object data = null;// 共享数据，只能有一个线程能写该数据，但可以有多个线程同时读该数据。
		private ReentrantReadWriteLock rwl = new ReentrantReadWriteLock();

		public void get() {
			rwl.readLock().lock();// 上读锁，其他线程只能读不能写
			System.out.println(Thread.currentThread().getName() + " be ready to read data!");
			try {
				Thread.sleep((long) (Math.random() * 1000));
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
			System.out.println(Thread.currentThread().getName() + "have read data :" + data);
			rwl.readLock().unlock(); // 释放读锁，最好放在finnaly里面
		}

		public void put(Object data) {
			rwl.writeLock().lock();// 上写锁，不允许其他线程读也不允许写
			System.out.println(Thread.currentThread().getName() + " be ready to write data!");
			try {
				Thread.sleep((long) (Math.random() * 1000));
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
			this.data = data;
			System.out.println(Thread.currentThread().getName() + " have write data: " + data);
			rwl.writeLock().unlock();// 释放写锁
		}
	}
}
